Temperature measurement and control for photohermal processes

• Main Authors: PENNEY; CARL M, CHANDE; TUSHAR S
• Format: Patent
• Language: English
• Published: 25.09.1990
• Subjects: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; COLORIMETRY; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT,POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRA-RED,VISIBLE OR ULTRA-VIOLET LIGHT; MEASURING; METALLURGY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; PHYSICS; RADIATION PYROMETRY; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TESTING; THEIR RELEVANT APPARATUS; TRANSPORTING

The temperature of a surface undergoing a radiation assisted thermally driven process is sensed by observation of the thermal emission from that surface and used to control the process. In a preferred embodiment, the blue edge of the thermal emission spectral distribution is detected to determine the surface temperature of a workpiece during a process such as laser-assisted chemical vapor deposition, and used to control this temperature. The temperature measuring system has means for focusing workpiece thermal emission and defining the field of view, a spectrometer to separate shorter wavelength light from other spectral components of the thermal emission, and a photon-counting system to detect the shorter wavelength light and generate a surface temperature signal. Systems to determine surface temperature at a spot and along a line have an optical prism to disperse the thermal emission into component wavelengths, and a multichannel photon-counting detector comprised of an intensified photodetector array.